function M = bool2fsa_dd1(B,alf0)
% converts a boolean expression for a dot-depth one language
% to a DFSA
% the following boolean expressions are legal:
% 1. [u0,u1,...,un]     with ui in \Sigma^*, corresponding to the
% "generalized shuffle ideal"
% 2. (a + b)   union, where a,b are boolean expressions
% 3. (a ^ b)   intersection, where a,b are boolean expressions
% 4. (a - b)   negation, where a,b are boolean expressions

% as always, @ stands for the empty word

ops = '()+-^[]';  % the operators
alf = ['@' ',' alf0];
if ~setcontains(union(alf,ops),B)
  error('Unknown characters used in expression');
end





% abusing the power of matlab:
B = ['(' B ')'];
alfplus = setplus(alf0);

STRS = text2cell_adv(B,alf,'');
OPRS = text2cell_adv(B,ops,'');

REG = OPRS{1};

for j=1:length(STRS)
  str = STRS{j};
  WRDS = text2cell_adv(str,'',',');
  if isempty(WRDS)
      R = alfplus;
  else
      R = WRDS{1};
      for s=2:length(WRDS)
          R = [R alfplus WRDS{s}];
      end
  end
  REG = [REG R OPRS{j+1}];
end

REG = strrep(REG,'@','');
REG = strrep(REG,'[','');
REG = strrep(REG,']','');


M = gregexp2dfsa_fast(REG,alf0);

return